Heat treatment of massecuite in mixer spouts



w. E. SMITH 2,172,040

Sept. 5, 1939.

BY HIS ATTORNEYS MMM.

WALTER E. SMITH Patented Sept. 5, 1939 UNITED STATES PATENT OFFICE HEAT TREATMENT OF MASSECUITE IN MIXER SPOUTS Walter E. Smith, Honolulu, Territory of Hawaii Application November 17, 1937, Serial No. 175,154

2 Claims. (01. 12719) This invention relates to the heat treatment of sugar bearing materials in the spouts of tanks containing such materials, such as the spouts of mixer tanks containing massecuite or magma.

5 More particularly, this invention is concerned with the provision of means for maintaining a predetermined temperature in mixer spouts and for control of such temperature in relation to the temperature of the massecuite within the tank.

In recent years much attention has been given to the purging of low grades of sugar and the separation of the sugar ,crystals from the molasses in which they are suspended. After evapol ration of the massecuite to ensure the crystallizacuite has a low temperature and is very viscous.

Reheating of the massecuite within the mixer increases the fluidity to such an extent that the massecuite may be effectively purged in the centrifugals. Althoughthe time of purging has been reduced and the quality of sugar produced has been improved by reheating the massecuite in the mixer, still there has remained an undesirable condition in the centrifuging. Unpredicta- 25 bly, the centrifugals would vibrate or oscillate in a dangerous fashion creating a terrific disturbance, often damaging the machine so that it had to be replaced or shut down for repairs. The unbalanced condition of the centrifugal seemed to occur, at times, in spite of the fact that the operator in charge of the centrifugal was experienced and possessed a high degree of skill gained by his having loaded it many times. The situa- 35 tion gave rise to the use of the expressions good sugar or bad sugar by the centrifugal operators, the bad sugar being that which caused the worst unbalanced condition and its most frequent occurrence.

40 Many efforts to overcome the unbalancing have been made. 'I'hesehave universally been in the nature of improvements to the centrifugal or its associated machinery. But neither the centrifugal operators nor the engineers and inventors 45 in the art realized wherein the fault lay. Hence they failed to solve the problem of unbalanced centrifugal operation.

Though many had noticed the retarded nature of the initial flow from the delivery spouts of the 50 mixer when the gates were opened to charge the centrifugal, it was generally thought that this was due to a settling of the sugar grains or to the absence of a velocity head at the moment of gate-opening. This condition was thought to be 55 unavoidable. No one realized that in this phetion of the greatest amount of sugar the massenomenon might be found the answer to the unbalancing of the centrifugal.

My invention lies in the discovery thatunbalanced centrifugal operation is not usually due to the machine itself but to the unequal viscosity 5 and hence unequal purging of all portions of the material loaded into the centrifugal basket.

I have discovered that the condition ofthe massecuite within the mixer spouts is not due to the concentration of the sugar grains but is due 10 to the fact that the relatively large heat radiating surface of the spouts has caused chilling of the massecuite in the spout and consequent increase in viscosity.

I have discovered, also, that this portion of massecuite with increased viscosity, even when the centrifugal is in charge of an experienced operator, is liable to cause unbalancing and dangerous oscillation of the centrifugal particularly if the massecuite contains high percentages of impurities of the type which are very viscous except at high temperatures. I have discovered that the massecuite in the mixer spout must be maintained at the same temperature as the main body of massecuite in the mixer if balanced centrifugal action is to be achieved. I have discovered that the provision of heating means broadly to raise the temperature of the massecuite in the mixer spout is insuflicien-t to ensure balanced centrifugal operation since the raising of the temperature of the body of massecuite in the spout higher than that of the body in the mixer tank will result in unequal purging.

Therefore it is an object of this invention to attain balanced centrifugal operation by ascertaining and correcting the cause of unbalanced operation.

Another object of my invention is to provide means for maintaining the temperature of the material in the mixer spout at the same tempera- 40 ture as that in the mixer itself.

Another object of my invention is to provide automatic means for regulatingthe temperature of the massecuite in the mixer spout and maintaining it at approximately the same temperature at the massecuite in the body of the mixer.

Other objects and advantages of my invention will become apparent as it is described in connection with the accompanying drawing.

In the drawing the single figure shows diagrammatically a mixer spout with a jacket for the circulation of heating water and means for maintaining it at the desired temperatureaccording to the principles of my invention.

Referring to the drawing the mixer tank In means of pivoted links 82 connected therewith and operated by a hand lever 86 in a well known fashion. Heretofore when the machine operator opened the gate and found the viscous portion of the massecuite in the spout to be slow in coming out he would move the gate up and down, chopping off portions of the massecuite as it bulged out, thus trying to distribute the viscous lump in small parts in the centrifugal. This procedure, however, was not satisfactory for the reason that very often the cool 'lump or lumps of viscous massecuite would remain in the centrifugal basket while the hot massecuite was purging and these lumps would be very slow to purge, causing the aforementioned unbalancing and oscillation of the centrifugal. This is one of the disadvantages that my present invention is designed to overcome. I

The mixer spout 14 may consist of a hollow casting of one or more parts which is provided with a chamber or passage I6 entirely around and within its walls for the circulation therein of hot water in order that the spout and material therein may be maintained at a desired temperature. The spout, in cross-section, is generally rectangular with rounded corners to facilitate casting. Opposite sides of the outside walls of the spout have large circular openings 20 over which are secured circular plates or covers, such as l8. The covers may be removed for the purpose of cleaning out the water jacket, as occasion requires. In each cover there is provided an opening into which is screwed a pipe joint, such as 22, to which may be connected pipes such as 24 and 26. The pipe 24 may be connected with the discharge of the pump 28 while the pipe 26 comprises the return to a reservoir or tank 30 containing hot water. This tank is connected with the intake of the pump 28 by a pipe 32.

being supplied to the coil through a pipe 36 containing a solenoid operated valve 38. A steam supply may be connected to the entrance chamber 46 of the valve by a pipe 42. An electrical solenoid 44' is mounted on top of the valve casing. The armature 46 of this solenoid is connected with the stem 48 of the valve and the stem 48 has on its lower end a valve head 50 adapted to fit upon a seat 52 provided therefor in the valve casing. A coil spring 54, acting on the armature 46, holds the valve normally open.

.For controlling the operation of the valve and its solenoid I have provided a thermostatic device' including a gas-filled metal bulb 60 inserted in I a wall of the mixer. This thermostatic device causes an electi'ical contact 62 to rise as the temperature of the massecuite rises and the gas within the bulb. expands. The details of the mechanism for causing movement of the contact The water in the tank is heated by a steam coil 34, the steam.

mote temperature readings or thermostatic controls. The contact 62 is connected by a wire 64 to one pole of a source of power (not shown). Also for controlling the solenoid 44 I have provided a thermostatic device including a gas-filled metal bulb 10 inserted in the wall of the hot water tank 36. This thermostatic device operates and is constructed similar to the thermostatic device 66 and is connected for operation of a movable electrical contact 72. This contact rises as the temperature increases inthe hot water tank 30. The contact is connected by a wire 14 to one end of the solenoid 44, the other end of the solenoid being connected by a wire 16 t0 the other pole of the source of power.

In operation, when the massecuite in the tank I0 becomes heated to a predetermined temperature -the thermostatic device 60 will cause the, contact 62 to rise and separate from the contact 12 as shown. This will break the circuit and deenergize the solenoid 44 which then will allow the valve to open by operation of the spring 54. Steam will thus be admitted to the coil 34 causing heating of the water in the tank 30. As the hot water is caused to circulate by the pump 2; through the pipes 32 and 24 and through the jacket or passage I6 around the mixer spout, the massecuite in the mixer spout will become heated. Preferably the water will be circulated in large volume through the jacket l6 at a temperature approximately equal to the temperature at which it is desired to maintain the massecuite in the spout. Therefore the thermostatic device 10 in the water tank will be set at a temperature slightly above the desired temperatureof the massecuite in the spout to provide for heat radiation as the a heating water circulates through the system. When the water in the hot water tank 30 has reached the desired temperature the thermostatic device 10 will cause the contact 12 to rise and engage with the contact 62 completing the circuit through the solenoid and causing the head 56 of the valve to press upon its seat 52, shutting ofi the supply of steam.

If the temperature of the massecuite in the mixer drops the contacts 62 and 12 will be maintained in engagement for a slightly longer period and until the water in the tank 36 has dropped sufficiently to cause the contact 12 to disengage the contact 62; and the steam supply will be shut ofi when the contact 12 re-engages the contact 62 in the lowered position of the contact 62. If the temperature of the massecuite in the mixer tank rises the contact 62 will rise and the contact 12 will have to rise farther before engaging it, thus allowing the steam to heat the water to a higher temperature before the valve closes. apparent that the means I have providedwill Thus it is.

maintain the temperature of the massecuite in the mixer spout at approximately the same temperature as the massecuite in the tank.

Obviously. many methods and types of apparatus for maintaining the temperatures of the massecuite in the spout and in the tank approximately equal will occur to those skilled in the art. Therefore I do not limit the invention to the specific embodiment shown.

I claim- 1. Apparatus for improving the operation of centrifugal machines when purging sugar-bearing materials that have been heated above atmospheric temperature in atank to increase their fluidity; said apparatus including a tank adapted to contain said heated sugar-bearing materials, a spout extending a substantial distance from the tank for delivering said material to a centrifugal, said spout having a chamber around it, and means for circulating heated fluid through said chamber at a temperature to keep the material in the spout at substantially the same temperature as the material in the tank.

2. Apparatus for improving the operation of centrifugal machines when purging sugar-bearing materials that have been heated above atmos- 10 pheric temperature in a tank to increase their fluidity, said apparatus including 5. an: adapted stantially equal to that of the material in the tank.

WALTER. E. SMITH.

- to contain said heated sugar-bearing materials, 

